1. Field of Invention
A large blow-molded plastic bottle of at least two liters, preferably 96 or 128 ounces, that includes an insert-type handle, has a height-to-diameter of less than 2:1, and expansion ratios that allow good moldability.
2. Description of Related Art
Food containers (bottles) of glass have been replaced by plastics for reasons of cost and safety. In particular, many containers with a capacity of one liter or more are now being manufactured from plastics (mainly, PET). At the beginning of development, due to cost and molding technology deficiencies, a large one gallon bottle (approximately four liters) was formed with a round shape, which was difficult to carry and had a handle affixed to the bottom of the mouth (or just below the neck) after the bottle was formed. However, a recent technology has been developed in which a bottle for shochu (e.g., liquor) or soy sauce is formed with a handle attached. In Japan, many large shochu containers and 1.8-litter soy sauce containers have been converted into containers with a handle.
Given this background, there arose a demand for a large bottle, such as a 96 oz. juice bottle, with a handle with which a customer could easily pour liquid. However, compared to a bottle of alcohol or the like, which is generally thin and long in order to have a sophisticated appearance, a beverage or food bottle is designed to be short, and shelves in supermarkets and convenience stores for such bottles are also designed to be shorter. Moreover, juice containers require high heat pasteurization processes and thus often require bottles having high heat resistance.
Attempts to affix a conventional handle to a large beverage or food bottle of two liters or more resulted in a very difficult design, with the overall height of the bottle becoming large as a solution.
A trend toward short bottles can be seen in Europe and in the United States. Particularly, in the United States, with respect to one gallon bottles, the height is approximately 290 mm compared to the Japanese two-liter bottle with a height of 305 mm. Despite being approximately double the capacity, the cost of these bottles is lower. While large diameter bottles with low height and an integrally molded handle are known, applicants are aware of no example of a large-diameter bottle with a low overall height using an insert-type handle.
There are problems with current bottles, particularly 96 oz. bottles. An explanation of these problems will be given below using as examples four bottles (see Table 1). Two of the bottles are large U.S. bottles of two liters (64 ounces) or more without insert-type handles. The last two bottles include a large four-liter bottle widely-used for shochu and a 1.8-liter bottle used for soy sauce. Both of the latter bottles are provided with an attached insert-type handle.
Table-1 shows the height of the bottles, excluding the mouth, and the maximum diameter of the above four conventional bottles. It can be seen that the height-to-diameter (H/D) ratio of a bottle with a handle (the 4 L shochu or 1.8 L soy sauce bottle) is more than 2:1. It would also be desirable to have insert-type handles on the other large bottles. However, the two bottles to which a handle is desirable (the 96 oz. and 1 gal. bottle), have a height-to-diameter (H/D) ratio that is less than 2:1. Thus, for these latter two bottles, the diameter is large and the height is short.
TABLE 1Ratio H/D between height (H) and bottle diameter (D)ShochuSoy Sauce4 liters1.8 liters1 gallon96 oz.(w/handle)(w/handle)(w/o handle)(w/o handle)Diameter (D)142106157140Height (H)345290266254H/D2.432.741.691.81Neck diameter (d)40.331.546.040.5D/d3.523.363.413.46
A bottle with an insert-type handle has not previously been realized when the height of the bottle was short and the diameter was thick, that is, when the H/D ratio was less than two.
A current method of forming a bottle having an insert-type handle involves inserting a preform, which has been heated to approximately 110° C., into a metal mold simultaneously with an insert handle and blow-molding the preform into a bottle (see FIGS. 1–2). During this molding, resin that has been molded is pressed into an undercut part of the insert-type handle 200, making it difficult for the handle 200 to come off.
With reference to FIG. 2, in such a molding method, if the outer diameter of the preform 100 contacts the handle 200, rubbing damage, scratching or the like occurs in the preform 100 and the handle 200, which results in a bottle 300 of lesser commercial value. Therefore, a distance 220 between the insert-type handle 200 and the preform 100 needs to be at least approximately 2 mm, and preferably approximately 5 mm. Additionally, a space 240 between the bottle 300 and a gripping part 260 of the handle should be at least 20 mm and preferably 25–30 mm, to allow a customer to easily grip the bottle by inserting his or her fingers into the space. Furthermore, when a bottle engaging part 280 of the handle and the gripping part 260 of the handle are combined, approximately 15–20 mm of space is needed. Accordingly, the maximum diameter or width of bottle 300 is the maximum diameter of preform 100 and the distance 220 between the handle 200 and preform 100 in addition to the total depth of handle 200. While the function of handle 200 can still be achieved if the handle protrudes from the maximum circumference of the bottle 300, this causes problems when the bottle needs to be boxed, and during a filling procedure in a bottle filling line. Therefore, it is preferable that handle 300 does not protrude from the maximum periphery of the bottle.
Taking the above into consideration, because the neck diameter d is substantially determined by the mouth diameter, the maximum diameter D of the bottle can be established by the following equation:D=(d/2+(35˜45)+2˜5)×2  (1)
With respect to the maximum diameter (D) of the bottle, when the mouth diameter is determined, the neck diameter logically follows. The exemplary soy sauce bottle and shochu bottles from Table 1 are calculated to have maximum diameters of 105.5 and 140.3, respectively, using equation 1. These numbers are close to the actual bottle diameters.
As described earlier, because the height of a bottle is determined in accordance with the height of an exhibition shelf, when the capacity of the bottle becomes large, the bottle accordingly has to be made larger in diameter.
However, for reasons relating to bottle moldability, the relationship H/D of the height and the diameter of the bottle for most bottles results in a H/D ratio of two or more. This is because, in extrusion blowing technology, the preform is stretched approximately twice its original length in a vertical direction and three to four times its original length in a horizontal direction to achieve appropriate expansion ratios in terms of bottle moldability. Furthermore, bottles that have been designed according to expansion ratios have a H/D ratio of 2 or more, and preferably 2.3.
The graph of FIG. 3 is a graph showing the relationship of the bottle height and volume (unit: ounces) of a heat resistant bottle in the United States. The solid line shows the current height of the bottle and a broken line shows a preferable height of the bottle, from the standpoint and objective of easy molding of the bottle.
According to this graph, even if the volume of the bottle becomes large, the height of the bottle does not become taller in proportion to the volume of the bottle. That is, when a bottle that needs a handle becomes 64 ounces (approximately 2 liters) or more, there is a tendency for the ratio of the height to the diameter/width to become smaller, and moldability accordingly decreases.
From the above description, it should be understood that a problem comes into existence when an insert-type handle is placed in a short bottle, as the handle constrains the size and shape of the preform used. It also will be understood that when a bottle 300 with a handle 200 is molded, the maximum diameter/width of the bottle is determined by a mouth diameter and the height of the bottle is determined by problems in molding.
The above description only discusses the external dimension aspect of the bottle. If the thickness of the bottle is ignored, the above theory is not related. If a bottle is made of a material such as a plastic bag, there is no problem, but in order to support a weight of two kilograms or more, it is necessary to have some thickness.
In terms of calculations, the desired expansion ratio can be accomplished if the thickness of the preform is made to be thick. However, when the thickness of preform 100 is more than 5 mm, using materials which are commonly available, the molding cycle becomes longer. In addition, this extra thickness causes a cooling insufficiency, which causes unclearness or cloudiness in the molded bottle 300. Therefore, it is not possible or desirable to make preform 100 very thick.
Because of the above problems, including size constraints of the preform 100 due to the provision of an insert-type handle 200 into the mold, the design of a preform 100 for a large bottle with an insert-type handle 200 and a H/D ratio of less than 2:1 is very difficult and the moldability of preform 100 is poor. That is, it is extremely difficult to form a bottle with an insert-type handle using this type of poor preform, and stable molding was not previously thought to be attainable.
Thus, the production of this type of large bottle with a low H/D ratio and an insert-type handle has not previously been realized.